Dental implants generally consist of an implant which is anchored within bone, and an abutment that is connected to the implant to support a prosthesis, such as a prosthetic tooth or denture. The abutment partially extends into the oral cavity in the position of the tooth it is to replace. The majority of dental implants are made of metal, usually titanium. Metal implants are easily threaded internally for attachment of prosthetic abutments. A problem with metal implants is that the coronal region of a metal implant shows through gum tissue as a dark shadow, thus making the prosthetic tooth look unnatural and unhealthy.
Ceramic implants are light in color, translucent, and appear more like natural tooth roots, thus avoiding the dark shadow found with metal implants. Gingival tissues typically attach quicker and more securely to ceramic than to titanium, thus providing a better seal around the neck of the implant. This improves the overall health of the implant site, for example, by avoiding infection and thus reducing the likelihood of implant rejection. However, there are a number of problems associated with ceramic implants. For example, dental implants are subjected to very high forces from mastication of food and, as a result, ceramic implants have a history of breakage due to their lack of tensile strength. Further, ceramic implants are typically manufactured as one-piece constructs of the implant and the abutment and, as a result, these implants are difficult to restore if the angulations or location of the surgical placement deviate from ideal.
Titanium dental implants with a ceramic sleeve cemented in the coronal region are known. There are several disadvantages to this design. If the ceramic sleeve is thin, it is fragile and the dark opaque metal of the implant shows through the gum making it appear less natural. If the ceramic sleeve is made thicker to overcome the problems with the thin ceramic sleeve, the implant diameter becomes too large for the implant site.
What is needed, and is not found in the prior art, is a dental implant that comprises both metal and ceramic to maximize the benefits of these two materials while avoiding the inherent weaknesses of the ceramic material.